Motors have a wide range of applications in modern industry and daily life, whether in home appliances, automation equipment, or power systems, we can see the figure of the motor. The working condition of the motor directly affects the operating efficiency and service life of the equipment, and ‘overload’ is one of the common problems of the motor in the process of use. This article will analyse the phenomenon of motor overload, causes and preventive measures to help readers better understand and deal with this problem.

A. What is motor overload?

Motor overload refers to the motor in the working process, the load exceeds its design carrying capacity, that is, the output power of the motor is greater than the rated power, resulting in a long time in the motor overload working state. When the motor is overloaded, it usually shows the following phenomena:

1. motor overheating: when the motor is overloaded, the heat generated exceeds the capacity of the heat sink, resulting in a continuous rise in motor temperature.

2. Abnormal sound: When the motor is overloaded, it may emit ear-splitting screech or knocking sound, which is due to the deformation of the motor's internal windings or other parts when they are subjected to excessive pressure.

3. increased vibration: motor overload will cause changes in the electromagnetic field, resulting in the motor rotor out of balance, increased vibration.

4. Increase in current: When a motor is overloaded, the current will increase significantly, often exceeding the rated value, which may cause a fuse to blow or a circuit breaker to trip.

5. Decrease in output power: When the motor is overloaded, the output power will be reduced, even to the point of not being able to achieve the desired operating results.

B. Causes of Motor Overload

There are various causes of motor overload, the common ones are as follows:

1. Excessive load: Sudden increase or continuous high level of external load, such as jamming of mechanical parts, mismatch of transmission system, etc., leads to the demand of motor output torque exceeding its design value.

2. abnormal power supply voltage: too low or fluctuating power supply voltage will affect the output power and torque characteristics of the motor, making the motor more susceptible to overload under the same load.

3. poor motor heat dissipation or high ambient temperature: motor running for a long time or high ambient temperature, coupled with poor ventilation, will lead to increased internal temperature of the motor, affecting insulation and cooling effect, which in turn reduces the output power of the motor, exacerbating the risk of overload.

4. Mechanical failure: bearing damage, rotor imbalance, stator-rotor friction and other mechanical failures, will increase the motor's internal losses and friction, so that the motor is easy to overload even under low loads.

5. Improper design and selection: The motor selection does not fully consider the actual working condition requirements, such as rated power, speed range, starting characteristics, etc., resulting in the selected motor and the actual load mismatch, easy to overload.

C. Effects of motor overload

1. Increase in temperature: Motor overload will cause the working temperature of the motor to increase beyond its temperature range, which may damage the insulation material of the motor and shorten the service life of the motor.

2. Increase in current: When overloaded, the motor will draw more current, resulting in high current. High current not only increases energy consumption, but may also cause damage to other components of the circuit system.

3. Decrease in efficiency: When the motor works under overload, the efficiency will be significantly reduced, which may lead to unstable operation of the equipment, or even shutdown phenomenon.

4. Damage to the motor: prolonged overload will lead to damage to the motor, especially for high efficiency, high load workplace motor, overload may lead to motor burnout or permanent damage.

D. How to prevent motor overload?

Preventing motor overloads is an important measure to ensure proper equipment operation and the safety of maintenance personnel. The following are some preventive measures that can be taken:

1. Reasonable selection of motors: When selecting a motor, the power and rated current of the motor should be reasonably selected according to the characteristics of the load and the working environment. Too small a motor is prone to overloading, while too large a motor will result in a waste of resources.

2. Regularly check the status of the motor: Regularly maintain and check the motor, including the insulation of the motor, the wiring status, current, voltage and so on. Abnormalities are found and dealt with in time to prevent overloading.

3. Installation of overload protection devices: modern motors are usually equipped with overload protection devices, such as overload relays, thermal protectors, etc. These devices can automatically cut off the power or alarm when the motor is overloaded, to avoid the motor from being overloaded for a long time.

4. Avoid frequent starting and stopping: too frequent starting and stopping will increase the load of the motor, try to avoid this operation, especially when the motor load is large. Use equipment such as soft starters to start the motor smoothly, which helps to reduce the risk of overload.

5. Optimise the working environment: Ensure that the working environment of the motor is at a suitable temperature and humidity, and ensure good ventilation, which will help the motor to dissipate heat and avoid overload caused by overheating.

6. Reasonable adjustment of the load: In practical applications, make sure that the motor load is within its rated range. If the load often exceeds the rated load of the motor, consideration should be given to increasing the motor power or improving the load conditions.

7. Optimise load distribution: Reasonably optimise load distribution to reduce the burden on individual motors and avoid overloading. For example, spread large loads over several smaller motors, or use efficient drive systems to reduce loads.

8. Training of operators: Train operators to understand the correct use of motors and precautions to avoid overloading of motors caused by misuse.

9. Timely handling of abnormal conditions: Timely detection and handling of abnormal conditions is also one of the important measures to prevent motor overload. For example, if the motor makes an abnormal sound or vibration increases, it should be stopped immediately to check and remove the fault.

E. Ways to deal with motor overload

Once the motor is found to be overloaded, measures should be taken immediately to deal with it:

1. Reduce the load: If the motor is overloaded due to an excessive load, the load should be reduced as much as possible. For example, stop unnecessary production activities and reduce the load on the equipment.

2. Adjust the voltage: If the motor overload is caused by a low supply voltage, try to adjust the supply voltage. However, please be careful not to adjust the supply voltage without authorisation as this may cause damage to the motor and other equipment.

3. Replace parts: If the motor overload is caused by worn or damaged parts, try replacing the parts. For example, if the bearings or other parts inside the motor are worn or damaged, consider replacing them with new ones.

4. restart the motor: if the motor is only temporarily overloaded, try restarting the motor. However, if the motor has been running continuously for a long period of time and is showing serious symptoms such as overheating, it should be shut down immediately and a professional should be called to inspect and repair it.

Conclusion

Motor overload not only affects the normal operation of the equipment, but also shortens the life of the motor and increases maintenance costs. Therefore, understanding the causes, effects and preventive measures of motor overload can effectively reduce motor failure and improve work efficiency. Through reasonable selection of motors, regular inspection, installation of protective devices and other means, we can minimise the occurrence of motor overload and ensure the safe and stable operation of the motor.

We hope that this article can help you better understand the knowledge of motor overload and pay attention to it in practical application to extend the service life of the motor and improve the efficiency of equipment operation.